This invention relates generally to doors for mine stoppings and, more particularly, to doors for use on masonry and metal mine stoppings.
So-called "stoppings" are widely used in mines to stop off the flow of air in passages in the mines, a "stopping" generally being a masonry (e.g., concrete block) or metal wall installed at the entrance of a passage to block flow of air therethrough. It is often desired that such stoppings be provided with a door for occasional access to the blocked-off passage. A problem is encountered, however, in providing a door for a stopping because the floors of passages in mines often heave up or otherwise shift (sometimes referred to as a "convergence"), which may result in the door becoming unlatched and opening up for undesired flow of air therethrough, or becoming jammed.
The door disclosed in applicants' U.S. Pat. No. 4,082,331, incorporated herein by reference, addresses the aforementioned problem in a generally satisfactory manner. The present invention represents an improvement with respect to the patented design.